This invention relates to a spring for the hinges of sun visors fitted to automobiles, in particular for tightening or holding support pins of such hinges.
The integration in the structures of the sun visors with which automobiles are normally equipped, of all kinds of technical novelties designed both for facilitating the driving of the vehicles and increasing the security and comfort conditions in the interior thereof, such as a passenger vanity mirror equipped with an electrical illumination device and even with a device for concealing the mirror itself, air freshening devices, etc., results in an increase in weight of such sun visors over those having a simple structure. Consequently, this increases the mechanical load acting mainly and specifically on the hinge support pin and on the tightening and holding means for such support pin. It is precisely the operation of such retaining or tightening means which allows the user to define the set positions of use of the sun visor. Up to date, such mechanical load, namely, the turning moment on the sun visor support pin compensated by the retaining or tightening means for the support pin, caused both by the sun visor and the devices contained therein and by the vibrations caused by the moving vehicle, generally reach values lying between 0.6 Nm and 1.2 Nm, with stable positions of use being obtained with the spring disclosed in Spanish utility model No. 292,644 (corresponding to U.S. Pat. No. 4,778,160).
The integration of devices offering greater service and housing also a wider range of components in the sun visor structures mean that, under the same conditions of use, the mechanical moment acting on the sun visor support pin exceeds the forementioned value of 1.2 Nm. This in turn means that with the use of the known support pin retaining or tightening means, the sun visor unit is positionally unstable, and may suddenly undesirably turn downwards, with the obvious drawbacks of all types that this represents, with reference to both comfort and to safety.